Determinants of trachoma endemicity using Chlamydia trachomatis ompA DNA sequencing

A six-year prospective study of Chlamydia trachomdtis infection and ocular disease in Tanzanian village children was conducted to identify the determinants of trachoma endemicity using sequencing of ompA. Overall, 749 conjunctival samples were obtained, with 176 children sampled in both 1989 and 1995. 31.1% (233/749) were positive by PCR-enzyme immunoassay, and 76% (176/ 233) of the positives were sequenced in variable domains (VD) 1 to 4 (22 children in both 1989 and 1995). Twenty-six ompA genotypes of serovar A, and w19 of B/Ba were identified, and only 20% of genotypes identified in 1995 matched those found in 1983. Tn particular, B/Ba genotypes exhibited a 15-base region in VD 2 with increased nucleotide substitution, and these types were associated with age load did predict subsequent severe trachoma (odds ratio (OR) = 10.14, 95% confidence interval (CI): 1.71, 60.23; OR = 6.40, 95% CI: 0.75, 54.41; OR = 6.74, 95% CI: 0.82, 55.38, respectively). And, multitypic infection was clustered with residence of village and associated with familial cattle ownership. In conclusion, high ompA polymorphism and the inability of some hosts to clear infection with the same ompA genotype suggest two distinct but converging mechanisms of endemic severe trachoma. (C) 2001 Editions scientifiques et medicales Elsevier SAS.